The aim of this study is to evaluate the effects of absorbent flow rate on CO2 absorption through a super hydrophobic hollow fiber contactor. The absorbent used in this study was a physical absorbent, namely a polyethyleneglycol-300 (PEG-300) solution. Meanwhile, the feed gases used in the experiments were pure CO2 and a mixture of 30% CO2 and 70% CH4. Gas absorption using a physical absorbent provides various benefits; for example, it can produce sufficiently high selectivity towards CO2 and it is less corrosive than chemical solvents. Three super hydrophobic hollow fiber contactors, each 6 cm in diameter and 25 cm in lengthconsist of 1000, 3000 and 5000 fibers, respectively, were used in this study. The type ofsuper hydrophobic fiber membrane used was polypropylene-based, with an outer and inner diameter of about 525 and 235 µm, respectively. During the experiments, the absorbent was flowed through the lumen fibers, whilst the feed gas flowed through the shell side of the membrane contactors. The experimental results showed that the mass transfer coefficient, the flux, and the absorption efficiency increased, but the CO2 loading decreased, with increasing absorbent flow rate in the membrane contactor. Meanwhile, it was found that an increase in the number of fibers in the membrane contactor, in general, will increase the absorption efficiency and the CO2 loading, but will decrease the overall mass transfer coefficient and the flux.

The membrane-based gas-liquid contactor is a suitable alternative technology for CO2 absorption from natural gas. Hydrophobicity is one of important properties of the membrane that prevents it being wetted by the absorbent solution. The super hydrophobic hollow fiber membrane contactors were utilized in this study to absorb CO2 using 5 vol.% PEG as an absorbent. The experimental results showed that the mass transfer coefficient, flux and absorption efficiency increased, but CO2 loading decreased, with increasing absorbent flow rate. The numbers of fibers in the contactor had different effects on mass transfer coefficient, flux and absorption efficiency. In general, the mass transfer coefficient and flux, at the same absorbent flow rate, decreased with increasing numbers of fibers in the membrane contactor. Meanwhile, the absorption efficiency and CO2 loading, at the same absorbent flow rate, increased with increasing numbers of fiber in the membrane contactor.

Acknowledgement

A part of this study was funded by the Directorate General of Higher Education Republic of Indonesia through Universitas Indonesia with contract No. 1178/UN2.R12/HKP.05.00/2016.